Jie Zhou et al.
Viral emissions into the air and environment after SARS-CoV-2 human challenge: a phase 1, open label, first-in-human study
The Lancet, June 2023 ; doi.org/10.1016/S2666-5247(23)00101-5
Abstract
Effectively implementing strategies to curb SARS-CoV-2 transmission requires understanding who is contagious and when. Although viral load on upper respiratory swabs has commonly been used to infer contagiousness, measuring viral emissions might be more accurate to indicate the chance of onward transmission and identify likely routes. We aimed to correlate viral emissions, viral load in the upper respiratory tract, and symptoms, longitudinally, in participants who were experimentally infected with SARS-CoV-2.
Methods
In this phase 1, open label, first-in-human SARS-CoV-2 experimental infection study at quarantine unit at the Royal Free London NHS Foundation Trust, London, UK, healthy adults aged 18–30 years who were unvaccinated for SARS-CoV-2, not previously known to have been infected with SARS-CoV-2, and seronegative at screening were recruited. Participants were inoculated with 10 50% tissue culture infectious dose of pre-alpha wild-type SARS-CoV-2 (Asp614Gly) by intranasal drops and remained in individual negative pressure rooms for a minimum of 14 days. Nose and throat swabs were collected daily. Emissions were collected daily from the air (using a Coriolis μ air sampler and directly into facemasks) and the surrounding environment (via surface and hand swabs). All samples were collected by researchers, and tested by using PCR, plaque assay, or lateral flow antigen test. Symptom scores were collected using self-reported symptom diaries three times daily. The study is registered with ClinicalTrials.gov, NCT04865237.
Findings
Between March 6 and July 8, 2021, 36 participants (ten female and 26 male) were recruited and 18 (53%) of 34 participants became infected, resulting in protracted high viral loads in the nose and throat following a short incubation period, with mild-to-moderate symptoms. Two participants were excluded from the per-protocol analysis owing to seroconversion between screening and inoculation, identified post hoc. Viral RNA was detected in 63 (25%) of 252 Coriolis air samples from 16 participants, 109 (43%) of 252 mask samples from 17 participants, 67 (27%) of 252 hand swabs from 16 participants, and 371 (29%) of 1260 surface swabs from 18 participants. Viable SARS-CoV-2 was collected from breath captured in 16 masks and from 13 surfaces, including four small frequently touched surfaces and nine larger surfaces where airborne virus could deposit. Viral emissions correlated more strongly with viral load in nasal swabs than throat swabs. Two individuals emitted 86% of airborne virus, and the majority of airborne virus collected was released on 3 days. Individuals who reported the highest total symptom scores were not those who emitted most virus. Very few emissions occurred before the first reported symptom (7%) and hardly any before the first positive lateral flow antigen test (2%).
Interpretation
After controlled experimental inoculation, the timing, extent, and routes of viral emissions was heterogeneous. We observed that a minority of participants were high airborne virus emitters, giving support to the notion of superspreading individuals or events. Our data implicates the nose as the most important source of emissions. Frequent self-testing coupled with isolation upon awareness of first symptoms could reduce onward transmissions.
Jie Zhou et al.
Viral emissions into the air and environment after SARS-CoV-2 human challenge: a phase 1, open label, first-in-human study
The Lancet, June 2023; doi.org/10.1016/S2666-5247(23)00101-5
Abstract
Effectively implementing strategies to curb SARS-CoV-2 transmission requires understanding who is contagious and when. Although viral load on upper respiratory swabs has commonly been used to infer contagiousness, measuring viral emissions might be more accurate to indicate the chance of onward transmission and identify likely routes. We aimed to correlate viral emissions, viral load in the upper respiratory tract, and symptoms, longitudinally, in participants who were experimentally infected with SARS-CoV-2.
Methods
In this phase 1, open label, first-in-human SARS-CoV-2 experimental infection study at quarantine unit at the Royal Free London NHS Foundation Trust, London, UK, healthy adults aged 18–30 years who were unvaccinated for SARS-CoV-2, not previously known to have been infected with SARS-CoV-2, and seronegative at screening were recruited. Participants were inoculated with 10 50% tissue culture infectious dose of pre-alpha wild-type SARS-CoV-2 (Asp614Gly) by intranasal drops and remained in individual negative pressure rooms for a minimum of 14 days. Nose and throat swabs were collected daily. Emissions were collected daily from the air (using a Coriolis μ air sampler and directly into facemasks) and the surrounding environment (via surface and hand swabs). All samples were collected by researchers, and tested by using PCR, plaque assay, or lateral flow antigen test. Symptom scores were collected using self-reported symptom diaries three times daily. The study is registered with ClinicalTrials.gov, NCT04865237.
Findings
Between March 6 and July 8, 2021, 36 participants (ten female and 26 male) were recruited and 18 (53%) of 34 participants became infected, resulting in protracted high viral loads in the nose and throat following a short incubation period, with mild-to-moderate symptoms. Two participants were excluded from the per-protocol analysis owing to seroconversion between screening and inoculation, identified post hoc. Viral RNA was detected in 63 (25%) of 252 Coriolis air samples from 16 participants, 109 (43%) of 252 mask samples from 17 participants, 67 (27%) of 252 hand swabs from 16 participants, and 371 (29%) of 1260 surface swabs from 18 participants. Viable SARS-CoV-2 was collected from breath captured in 16 masks and from 13 surfaces, including four small frequently touched surfaces and nine larger surfaces where airborne virus could deposit. Viral emissions correlated more strongly with viral load in nasal swabs than throat swabs. Two individuals emitted 86% of airborne virus, and the majority of airborne virus collected was released on 3 days. Individuals who reported the highest total symptom scores were not those who emitted most virus. Very few emissions occurred before the first reported symptom (7%) and hardly any before the first positive lateral flow antigen test (2%).
Interpretation
After controlled experimental inoculation, the timing, extent, and routes of viral emissions was heterogeneous. We observed that a minority of participants were high airborne virus emitters, giving support to the notion of superspreading individuals or events. Our data implicates the nose as the most important source of emissions. Frequent self-testing coupled with isolation upon awareness of first symptoms could reduce onward transmissions.
Nieves Derqui et al.
Risk factors and vectors for SARS-CoV-2 household transmission: a prospective, longitudinal cohort study
The Lancet, April 2023; doi.org/10.1016/S2666-5247(23)00069-1
Abstract
Despite circumstantial evidence for aerosol and fomite spread of SARS-CoV-2, empirical data linking either pathway with transmission are scarce. Here we aimed to assess whether the presence of SARS-CoV-2 on frequently-touched surfaces and residents' hands was a predictor of SARS-CoV-2 household transmission.
Methods
In this longitudinal cohort study, during the pre-alpha (September to December, 2020) and alpha (B.1.1.7; December, 2020, to April, 2021) SARS-CoV-2 variant waves, we prospectively recruited contacts from households exposed to newly diagnosed COVID-19 primary cases, in London, UK. To maximally capture transmission events, contacts were recruited regardless of symptom status and serially tested for SARS-CoV-2 infection by RT-PCR on upper respiratory tract (URT) samples and, in a subcohort, by serial serology. Contacts' hands, primary cases' hands, and frequently-touched surface-samples from communal areas were tested for SARS-CoV-2 RNA. SARS-CoV-2 URT isolates from 25 primary case-contact pairs underwent whole-genome sequencing (WGS)
Findings
From Aug 1, 2020, until March 31, 2021, 620 contacts of PCR-confirmed SARS-CoV-2-infected primary cases were recruited. 414 household contacts (from 279 households) with available serial URT PCR results were analysed in the full household contacts' cohort, and of those, 134 contacts with available longitudinal serology data and not vaccinated pre-enrolment were analysed in the serology subcohort. Household infection rate was 28·4% (95% CI 20·8–37·5) for pre-alpha-exposed contacts and 51·8% (42·5–61·0) for alpha-exposed contacts (p=0·0047). Primary cases' URT RNA viral load did not correlate with transmission, but was associated with detection of SARS-CoV-2 RNA on their hands (p=0·031). SARS-CoV-2 detected on primary cases' hands, in turn, predicted contacts' risk of infection (adjusted relative risk [aRR]=1·70 [95% CI 1·24–2·31]), as did SARS-CoV-2 RNA presence on household surfaces (aRR=1·66 [1·09–2·55]) and contacts' hands (aRR=2·06 [1·57–2·69]). In six contacts with an initial negative URT PCR result, hand-swab (n=3) and household surface-swab (n=3) PCR positivity preceded URT PCR positivity. WGS corroborated household transmission.
Interpretation
Presence of SARS-CoV-2 RNA on primary cases' and contacts' hands and on frequently-touched household surfaces associates with transmission, identifying these as potential vectors for spread in households.
Melisa M Shah et al.
Occupations Associated With Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Vaccination, US Blood Donors, May 2021–December 2021
CID, November 2022; doi.org/10.1093/cid/ciac883
Abstract
There are limited data on the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the United States by occupation. We identified occupations at higher risk for prior SARS-CoV-2 infection as defined by the presence of infection-induced antibodies among US blood donors.
Methods
Using a nested case-control study design, blood donors during May–December 2021 with anti-nucleocapsid (anti-N) testing were sent an electronic survey on employment status, vaccination, and occupation. The association between previous SARS-CoV-2 infection and occupation-specific in-person work was estimated using multivariable logistic regression adjusting for sex, age, month of donation, race and ethnicity, education, vaccination, and telework.
Conclusions
Workers in healthcare, protective services, and food preparation had the highest prevalence of prior SARS-CoV-2 infection. Occupational risks for SARS-CoV-2 infection remained after adjusting for vaccination, telework, and demografic factors. These findings underscore the need for mitigation measures and personal protection in healthcare setting and other workplace.
Yang Wang et al.
SARS-CoV-2 Exposure in Norway Rats (Rattusnorvegicus) from New York City
https://journals.asm.org/doi/10.1128/mbio.03621-22?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed
Abstract
Millions of Norway rats (Rattusnorvegicus) inhabit New York City (NYC), presenting the potential for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from humans to rats. We evaluated SARS-CoV-2 exposure among 79 rats captured from NYC during the fall of 2021. Our results showed that 13 of the 79 rats (16.5%) tested IgG- or IgM-positive, and partial SARS-CoV-2 genomes were recovered from all 4 rats that were qRT-PCR (reverse transcription-quantitative PCR)-positive. Genomic analyses suggest these viruses were associated with genetic lineage B, which was predominant in NYC in the spring of 2020 during the early pandemic period. To further investigate rat susceptibility to SARS-CoV-2 variants, we conducted a virus challenge study and showed that Alpha, Delta, and Omicron variants can cause infections in wild-type Sprague Dawley (SD) rats, including high replication levels in the upper and lower respiratory tracts and induction of both innate and adaptive immune responses. Additionally, the Delta variant resulted in the highest infectivity. In summary, our results indicate that rats are susceptible to infection with Alpha, Delta, and Omicron variants, and wild Norway rats in the NYC municipal sewer systems have been exposed to SARS-CoV-2. Our findings highlight the need for further monitoring of SARS-CoV-2 in urban rat populations and for evaluating the potential risk of secondary zoonotic transmission from these rat populations back to humans.
IMPORTANCE The host tropism expansion of SARS-CoV-2 raises concern for the potential risk of reverse-zoonotic transmission of emerging variants into rodent species, including wild rat species. In this study, we present both genetic and serological evidence for SARS-CoV-2 exposure to the New York City wild rat population, and these viruses may be linked to the viruses that were circulating during the early stages of the pandemic. We also demonstrated that rats are susceptible to additional variants (i.e., Alpha, Delta, and Omicron) that have been predominant in humans and that susceptibility to infection varies by variant. Our findings highlight the reverse zoonosis of SARS-CoV-2 to urban rats and the need for further monitoring of SARS-CoV-2 in rat populations for potential secondary zoonotic transmission to humans.
Mark Loeb et al.
Medical Masks Versus N95 Respirators for Preventing COVID-19 Among Health Care Workers
https://www.acpjournals.org/doi/10.7326/M22-1966
Abstract
Background:
It is uncertain if medical masks offer similar protection against COVID-19 compared with N95 respirators.
Objective:
To determine whether medical masks are noninferior to N95 respirators to prevent COVID-19 in health care workers providing routine care.
Design:
Multicenter, randomized, noninferiority trial. (ClinicalTrials.gov: NCT04296643).
Setting:
29 health care facilities in Canada, Israel, Pakistan, and Egypt from 4 May 2020 to 29 March 2022.
Participants:
1009 health care workers who provided direct care to patients with suspected or confirmed COVID-19.
Intervention:
Use of medical masks versus fit-tested N95 respirators for 10 weeks, plus universal masking, which was the policy implemented at each site.
Measurements:
The primary outcome was confirmed COVID-19 on reverse transcriptase polymerase chain reaction (RT-PCR) test.
Results:
In the intention-to-treat analysis, RT-PCR–confirmed COVID-19 occurred in 52 of 497 (10.46%) participants in the medical mask group versus 47 of 507 (9.27%) in the N95 respirator group (hazard ratio [HR], 1.14 [95% CI, 0.77 to 1.69]). An unplanned subgroup analysis by country found that in the medical mask group versus the N95 respirator group RT-PCR–confirmed COVID-19 occurred in 8 of 131 (6.11%) versus 3 of 135 (2.22%) in Canada (HR, 2.83 [CI, 0.75 to 10.72]), 6 of 17 (35.29%) versus 4 of 17 (23.53%) in Israel (HR, 1.54 [CI, 0.43 to 5.49]), 3 of 92 (3.26%) versus 2 of 94 (2.13%) in Pakistan (HR, 1.50 [CI, 0.25 to 8.98]), and 35 of 257 (13.62%) versus 38 of 261 (14.56%) in Egypt (HR, 0.95 [CI, 0.60 to 1.50]). There were 47 (10.8%) adverse events related to the intervention reported in the medical mask group and 59 (13.6%) in the N95 respirator group.
Limitation:
Potential acquisition of SARS-CoV-2 through household and community exposure, heterogeneity between countries, uncertainty in the estimates of effect, differences in self-reported adherence, differences in baseline antibodies, and between-country differences in circulating variants and vaccination.
Conclusion:
Among health care workers who provided routine care to patients with COVID-19, the overall estimates rule out a doubling in hazard of RT-PCR–confirmed COVID-19 for medical masks when compared with HRs of RT-PCR–confirmed COVID-19 for N95 respirators. The subgroup results varied by country, and the overall estimates may not be applicable to individual countries because of treatment effect heterogeneity.
Jianyu Lai et al.
Exhaled Breath Aerosol Shedding of Highly Transmissible Versus Prior Severe Acute Respiratory Syndrome Coronavirus 2 Variants
CID, October 2022; doi.org/10.1093/cid/ciac846
Abstract
Background
Aerosol inhalation is recognized as the dominant mode of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. Three highly transmissible lineages evolved during the pandemic. One hypothesis to explain increased transmissibility is that natural selection favors variants with higher rates of viral aerosol shedding. However, the extent of aerosol shedding of successive SARS-CoV-2 variants is unknown. We aimed to measure the infectivity and rate of SARS-CoV-2 shedding into exhaled breath aerosol (EBA) by individuals during the Delta and Omicron waves and compared those rates with those of prior SARS-CoV-2 variants from our previously published work.
Methods
Individuals with coronavirus disease 2019 (COVID-19) (n = 93; 32 vaccinated and 20 boosted) were recruited to give samples, including 30-minute breath samples into a Gesundheit-II EBA sampler. Samples were quantified for viral RNA using reverse-transcription polymerase chain reaction and cultured for virus.
Results
Alpha (n = 4), Delta (n = 3), and Omicron (n = 29) cases shed significantly more viral RNA copies into EBAs than cases infected with ancestral strains and variants not associated with increased transmissibility (n = 57). All Delta and Omicron cases were fully vaccinated and most Omicron cases were boosted. We cultured virus from the EBA of 1 boosted and 3 fully vaccinated cases.
Conclusions
Alpha, Delta, and Omicron independently evolved high viral aerosol shedding phenotypes, demonstrating convergent evolution. Vaccinated and boosted cases can shed infectious SARS-CoV-2 via EBA. These findings support a dominant role of infectious aerosols in transmission of SARS-CoV-2. Monitoring aerosol shedding from new variants and emerging pathogens can be an important component of future threat assessments and guide interventions to prevent transmission.
Pamela Leece et al.
Nursing home crowding and its association with outbreak-associated respiratory infection in Ontario, Canada before the COVID-19 pandemic (2014–19): a retrospective cohort study
The Lancet, March 2023; doi.org/10.1016/S2666-7568(23)00018-1
Abstract
Background
Studies conducted during the COVID-19 pandemic have shown that crowding in nursing homes is associated with high incidence of SARS-CoV-2 infections, but this effect has not been shown for other respiratory pathogens. We aimed to measure the association between crowding in nursing homes and outbreak-associated respiratory infection incidence and related mortality before the COVID-19 pandemic.
Interpretation
Respiratory infection and mortality rates were higher in nursing homes with high crowding index than in homes with low crowding index, and the association was consistent across various respiratory pathogens. Decreasing crowding is an important safety target beyond the COVID-19 pandemic to help to promote resident wellbeing and decrease the transmission of prevalent respiratory pathogens.
ZhuxunLiu et al.
A numerical study of COVID-19-laden droplets dispersion in aircraft cabin ventilation system
Cell, February 2023; doi.org/10.1016/j.heliyon.2023.e13920
Abstract
Ventilation systems for aircraft cabins are mainly used to maintain a comfortable environment in the cabin and ensure the health of passengers. This study evaluates the decontamination performance of two cabin ventilation systems, the displacement ventilation (DV) system and the mixing ventilation (MV) system, in preventing contamination by virus (COVID-19)-laden droplets. The Euler-Lagrange method was used to computationally model droplet dispersion of different diameters and their behavior in the two systems was contrastively analyzed. Statistics on droplet suspension ratios and duration as well as the infection probability of each passenger were also computed. It was found that11.07% fewer droplet remained suspended in the DV system were than those in the MV system 10s from droplet release. In addition, the number of droplets extracted from the exhausts in the DV system was 13.15% more than the MV system at the 400s mark. In the DV system, higher ambient wind velocities were also found to locally increase infection probability for passengers in certain locations.
Hannah McClymon et al.
Using weather factors and google data to predict COVID-19 transmission in Melbourne, Australia: A time-series predictive model
Cell, February 2023; doi.org/10.1016/j.heliyon.2023.e13782
Abstract
Background
Forecast models have been essential in understanding COVID-19 transmission and guiding public health responses throughout the pandemic. This study aims to assess the effect of weather variability and Google data on COVID-19 transmission and develop multivariable time series AutoRegressive Integrated Moving Average (ARIMA) models for improving traditional predictive modelling for informing public health policy.
Conclusion
Multivariable ARIMA modelling for COVID-19 cases and Reff was useful for predicting epidemic growth, with higher predictive accuracy for models including TSM and Tmax. These results suggest that TSM and Tmax would be useful for further exploration for developing weather-informed early warning models for future COVID-19 outbreaks with potential application for the inclusion of weather and Google data with disease surveillance in developing effective early warning systems for informing public health policy and epidemic response.
Conforti A. et al.
A linear DNA vaccine candidate encoding the SARS-CoV-2 Receptor Binding Domain elicits potent immune response and neutralizing antibodies in domestic cats
Cell, January2023; doi.org/10.1016/j.omtm.2022.12.015
Abstract
SARS-CoV-2, the etiologic agent of COVID-19 pandemic, has been shown to infect a wide range of animal species, especially mammals, and besides human-to-human transmission, also human-to-animal transmission has been observed in some wild animals and pets, especially in cats. It has been demonstrated that cats are permissive to COVID-19 and are susceptible to airborne infections. Given the high transmissibility potential of SARS-CoV-2 to different host species and the close contact between humans and animals, it is crucial to find mechanisms to prevent the transmission chain and reduce the risk of spillover to susceptible species. Here, we show results from a clinical trial conducted in domestic cats to assess safety and immunogenicity of a linear DNA (“linDNA”) vaccine encoding the Receptor Binding Domain (RBD) from SARS-CoV-2 (Lin-Covid-eVax). Lin-Covid-eVax proved to be safe, with no significant adverse events and able to elicit both RBD-specific antibodies and T cells. Also, the linDNA vaccine induced neutralizing antibody titers against ancestral SARS-CoV-2 virus and its variants. These findings demonstrate the safety and immunogenicity of a genetic vaccine against COVID-19 administered to cats and strongly support the development of vaccines for preventing viral spread in susceptible species, especially those in close contact with humans.
Atle Fretheim et al.
Effect of Wearing Glasses on Risk of Infection With SARS-CoV-2 in the Community A Randomized Clinical Trial
Lancet, December 2022; doi:10.1001/jamanetworkopen.2022.44495
Abstract
Importance Observational studies have reported an association between the use of eye protection and reduced risk of infection with SARS-CoV-2 and other respiratory viruses, but, as with most infection control measures, no randomized clinical trials have been conducted.
Objectives To evaluate the effectiveness of wearing glasses in public as protection against being infected with SARS-CoV-2 and other respiratory viruses.
Design, Setting, and Participants A randomized clinical trial was conducted in Norway from February 2 to April 24, 2022; all adult members of the public who did not regularly wear glasses, had no symptoms of COVID-19, and did not have COVID-19 in the last 6 weeks were eligible.
Intervention Wearing glasses (eg, sunglasses) when close to others in public spaces for 2 weeks.
Main Outcomes and Measures The primary outcome was a positive COVID-19 test result reported to the Norwegian Surveillance System for Communicable Diseases. Secondary outcomes included a positive COVID-19 test result and respiratory infection based on self-report. All analyses adhered to the intention-to-treat principle.
Conclusions and Relevance In this randomized clinical trial, wearing glasses in the community was not protective regarding the primary outcome of a reported positive COVID-19 test. However, results were limited by a small sample size and other issues. Glasses may be worth considering as one component in infection control, pending further studies.
Cowger T.L. et al.
Lifting Universal Masking in Schools — Covid-19 Incidence among Students and Staff
NEJM, November 2022; DOI:10.1056/NEJMoa2211029
Abstract
BACKGROUND In February 2022, Massachusetts rescinded a statewide universal masking policy in public schools, and many Massachusetts school districts lifted masking requirements during the subsequent weeks. In the greater Boston area, only two school districts — the Boston and neighboring Chelsea districts — sustained masking requirements through June 2022. The staggered lifting of masking requirements provided an opportunity to examine the effect of universal masking policies on the incidence of coronavirus disease 2019 (Covid-19) in schools. METHODS We used a difference-in-differences analysis for staggered policy implementation to compare the incidence of Covid-19 among students and staff in school districts in the greater Boston area that lifted masking requirements with the incidence in districts that sustained masking requirements during the 2021–2022 school year. Characteristics of the school districts were also compared. RESULTS Before the statewide masking policy was rescinded, trends in the incidence of Covid-19 were similar across school districts. During the 15 weeks after the statewide masking policy was rescinded, the lifting of masking requirements was associated with an additional 44.9 cases per 1000 students and staff (95% confidence interval, 32.6 to 57.1), which corresponded to an estimated 11,901 cases and to 29.4% of the cases in all districts during that time. Districts that chose to sustain masking requirements longer tended to have school buildings that were older and in worse condition and to have more students per classroom than districts that chose to lift masking requirements earlier. In addition, these districts had higher percentages of low-income students, students with disabilities, and students who were English-language learners, as well as higher percentages of Black and Latinx students and staff. Our results support universal masking as an important strategy for reducing Covid-19 incidence in schools and loss of in-person school days. As such, we believe that universal masking may be especially useful for mitigating effects of structural racism in schools, including potential deepening of educational inequities. CONCLUSIONS Among school districts in the greater Boston area, the lifting of masking requirements was associated with an additional 44.9 Covid-19 cases per 1000 students and staff during the 15 weeks after the statewide masking policy was rescinded.
N.K. Love et al.
Daily use of lateral flow devices by contacts of confirmed COVID-19 cases to enableexemption from isolationcompared with standard self-isolation to reduce onward transmission of SARS-CoV-2 in England: a randomised, controlled, non-inferiority trial
Lancet Respiratory Medicine, October2022; doi: 10.1016/S2213-2600(22)00267-3
Abstract
During the study period (April to July, 2021), allcontacts of people with COVID-19 wererequired to self-isolate for 10 days. The authorsinvestigatedwhetherdaily use of lateral flow devices (LFDs) to test for SARS-CoV-2, with removal of self-isolation for 24 h if negative, could be a safe alternative to self-isolationas a means to minimiseonward transmission of the virus.
S. Hakki S. et al.
Onset and window of SARS-CoV-2 infectiousness and temporalcorrelation with symptomonset: a prospective, longitudinal, community cohort study
Lancet Respiratory Medicine, August 2022; doi: 10.1016/S2213-2600(22)00226-0
Abstract
Knowledge of the window of SARS-CoV-2 infectiousnessiscrucial in developing policies to curb transmission. Mathematical modellinghasdrivenisolation and testing policy, butweneedreal-world data. The authorsaimed to characteriseinfectiousnessacross the full course of infection in a real-world community setting.
M. Mortazavi et al.
SARS-CoV-2 pseudotyped virus persists on the surface of multiple produce but can be inactivated with gaseous ozone
Heliyon, August 2022; doi.org/10.1016/j.heliyon.2022.e10280
Abstract
Due to the immense societal and economic impact that the COVID-19 pandemic has caused, limiting the spread of SARS-CoV-2 is one of the most important priorities at this time. The global interconnectedness of the food industry makes it one of the biggest concerns for SARS-CoV-2 outbreaks. Although fomites are currently considered a low-risk route of transmission for SARS-CoV-2, new variants of the virus can potentially alter the transmission dynamics. In this study, we compared the survival rate of pseudotyped SARS-CoV-2 on plastic with some commonly used food samples (i.e., apple, strawberry, grapes, tomato, cucumber, lettuce, parsley, Brazil nut, almond, cashew, and hazelnut). The porosity level and the chemical composition of different food products affect the virus's stability and infectivity. Our results showed that tomato, cucumber, and apple offer a higher survival rate for the pseudotyped viruses. Next, we explored the effectiveness of ozone in deactivating the SARS-CoV-2 pseudotyped virus on the surface of tomato, cucumber, and apple. We found that the virus was effectively inactivated after being exposed to 15 ppm of ozone for 1 h under ambient conditions. SEM imaging revealed that while ozone exposure altered the wax layer on the surface of produce, it did not seem to damage the cells and their biological structures. The results of our study indicate that ozonated air can likely provide a convenient method of effectively disinfecting bulk food shipments that may harbour the SARS-CoV-2 virus.
P. Skendros et al.
Complement C3 inhibition in severe COVID-19 using compstatin AMY-101
Science Advances, August 2022; doi: 10.1126/sciadv.abo2341
Abstract
Complement C3 activation contributes to COVID-19 pathology, and C3 targeting has emerged as a promising therapeutic strategy. We provide interim data from ITHACA, the first randomized trial evaluating a C3 inhibitor, AMY-101, in severe COVID-19 (PaO2/FiO2 ≤ 300 mmHg). Patients received AMY-101 (n = 16) or placebo (n = 15) in addition to standard of care. AMY-101 was safe and well tolerated. Compared to placebo (8 of 15, 53.3%), a higher, albeit nonsignificant, proportion of AMY-101–treated patients (13 of 16, 81.3%) were free of supplemental oxygen at day 14. Three nonresponders and two placebo-treated patients succumbed to disease-related complications. AMY-101 significantly reduced CRP and ferritin and restrained thrombin and NET generation. Complete and sustained C3 inhibition was observed in all responders. Residual C3 activity in the three nonresponders suggested the presence of a convertase-independent C3 activation pathway overriding the drug’s inhibitory activity. These findings support the design of larger trials exploring the potential of C3-based inhibition in COVID-19 or other complement-mediated diseases.
J. P. Rogers et al.
Neuropsychiatric sequelae of COVID-19: long-lasting, but not uniform
Lancet Psychiatry, August 2022; doi: 10.1016/S2215-0366(22)00302-9
Abstract
Early in the COVID-19 pandemic, in our research group we reviewed the psychiatric outcomes of individuals who had been infected by one of two previous coronavirus epidemics: severe acute respiratory syndrome (known as SARS) and Middle East respiratory syndrome (known as MERS). The main weakness of the previous literature was the absence of any valid comparison group. Symptoms such as insomnia, anxiety, mood changes, impaired concentration, irritability, fatigue, and traumatic memories were common, and still reported months and years after initial diagnosis.
D. Adam
How long is COVID infectious? What scientists know so far
Nature News, July 2022; https://www.nature.com/articles/d41586-022-02026-x
Abstract
When the US Centers for Disease Control and Prevention (CDC) halved its recommended isolation time for people with COVID-19 to five days back in December, it said that the change was motivated by science. Specifically, the CDC said that most SARS-CoV-2 transmission occurs early in the course of the illness, in the one to two days before the onset of symptoms and for two to three days after. Many scientists disputed that decision then and they continue to do so. Such dissent is bolstered by a series of studies confirming that many people with COVID-19 remain infectious well into the second week after they first experience symptoms.
J. Boucau et al.
Duration of viable virus shedding in SARS-CoV-2 omicron variant infection
medRxiv, march 2022; doi.org/10.1101/2022.03.01.22271582
Abstract
Clinical features of SARS-CoV-2 Omicron variant infection, including incubation period and transmission rates, distinguish this variant from preceding variants. However, whether the duration of shedding of viable virus differs between omicron and previous variants is not well understood. To characterize how variant and vaccination status impact shedding of viable virus, we serially sampled symptomatic outpatients newly diagnosed with COVID-19. Anterior nasal swabs were tested for viral load, sequencing, and viral culture. Time to PCR conversion was similar between individuals infected with the Delta and the Omicron variant. Time to culture conversion was also similar, with a median time to culture conversion of 6 days (interquartile range 4-8 days) in both groups. There were also no differences in time to PCR or culture conversion by vaccination status.
O. Puhach et al.
Infectious viral load in unvaccinated and vaccinated individuals infected with ancestral, Delta or Omicron SARS-CoV-2.
Nature Medicine, April (2022); doi.org/10.1038/s41591-022-01816-0
Abstract
Infectious viral load (VL) expelled as droplets and aerosols by infected individuals partly determines SARS-CoV-2 transmission. RNA VL measured by qRT-PCR is only a weak proxy for infectiousness. Studies on the kinetics of infectious VL are important to understand the mechanisms behind the different transmissibility of SARS-CoV-2 variants and the effect of vaccination on transmission, which allows to guide public health measures. In this study we quantified infectious VL in SARS-CoV-2 infected individuals during the first 5 symptomatic days by in vitro culturability assay in unvaccinated or vaccinated individuals infected with pre-variant of concern (pre-VOC) SARS-CoV-2, Delta, or Omicron. Unvaccinated individuals infected with pre-VOC SARS-CoV-2 had lower infectious VL compared to Delta-infected unvaccinated individuals. Full vaccination (defined as >2weeks after reception of 2nd dose during primary vaccination series) significantly reduced infectious VL for Delta breakthrough cases compared to unvaccinated individuals. For Omicron breakthrough cases, reduced infectious VL was only observed in boosted but not in fully vaccinated individuals compared to unvaccinated subjects. In addition, infectious VL was lower in fully vaccinated Omicron- compared to fully vaccinated Delta-infected individuals, suggesting that other mechanisms than increased infectious VL contribute to the high infectiousness of SARS-CoV-2 Omicron. Our findings indicate that vaccines may lower transmission risk and therefore have a public health benefit beyond the individual protection from severe disease.
D. Lewis
Perché l'OMS ha impiegato due anni per dire che COVID-19 si trasmette per via aerea
Nature, 12 aprile 2022
Abstract
All'inizio della pandemia, l'Organizzazione mondiale della Sanità ha dichiarato che SARS-CoV-2 non si trasmetteva attraverso l'aria. Quell'errore e il prolungato processo di correzione hanno seminato confusione e sollevano domande su che cosa accadrà nella prossima emergenza pandemica.
Kolodziej LM et al.
SARS-CoV-2 transmission risk upon return to work in RNA-positive healthcare workers
J Hosp Infect.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8916832/pdf/main.pdf
CONTENUTO E COMMENTO : In questo studio prospettico osservazionale viene valutata la capacità di trasmissione del virus SARS-CoV-2 di operatori sanitari che rientrano a lavoro dopo l’infezione da SARS-CoV-2. Sono stati arruolati operatori sanitari non vaccinati per SARS-CoV-2 (da maggio a settembre 2020) con un tampone nasofaringeo molecolare positivo. Al rientro a lavoro (dopo almeno 24 ore dalla risoluzione dei sintomi respiratori, in accordo con le procedure interne dell’ospedale di riferimento) è stato ripetuto il tampone nasofaringeo molecolare per SARS-CoV-2. Per gli operatori sanitari risultati positivi al tampone nasofaringeo di controllo sono state effettuate analisi filogenetiche per valutare possibili trasmissioni sul posto di lavoro. Sessantuno (84.7%) partecipanti hanno avuto un tampone di controllo positivo (mediana 13 giorni dall’esordio dei sintomi), il 49.1% dei quali con una mediana di cicli soglia di 29.2. Undici colleghi diretti di sei partecipanti con tampone positivo al rientro con cicli soglia <30 sono risultati positivi; tuttavia le analisi epidemiologiche e filogenetiche non hanno mostrato alcuna trasmissione legata al partecipante indice.
Stabilire la contagiosità di un soggetto con recente infezione da SARS-CoV-2 è una questione di fondamentale importanza e numerosi studi hanno dimostrato la scarsa capacità del tampone molecolare nel decretare la fine del periodo di contagiosità. L’approccio basato sulla assenza di sintomatologia per stabilire il rientro a lavoro degli operatori sanitari proposto dagli autori dello studio dovrebbe tuttavia essere integrato con un test di laboratorio, come ad esempio il tampone antigenico che sembrerebbe più accurato del tampone molecolare nello stabilire il periodo di infettività.
